On Tue, 23 Sep 2003 09:13:28 +1000, "dixie" <di****@dogmail.com>

wrote:

Here is one option:

Turn the string into a number (e.g. by stripping all non-numerics).

Call this number A. Then calculate the difference between that number

and the number 123456789 (or any other "magic number") called number

B. The user would have to enter the resulting number C (=A-B) in order

to enable the software.

Variants:

* A is created not just by stripping the non-numerics, but these

non-numerics actually modify the numerics. E.g. A adds 1, B adds 2,

etc.

* B is modified by the non-numerics in a similar way.

* C is modified by the current date (e.g. subtract the number of days

in the current year) so the code can be used only once.

The sky is the limit in how complicated you can make these algorithms.

Happy programming.

-Tom.

Is there some relatively simple way that I could create some sort of number

from a series of letters and numbers in a field on a form and then when a

person purchases the software, supply a matching number to their unique

number that could be put into a field in a table that would then enable the

software.

I think the idea would probably work, but how do I generate the number. The

number would come from something like A03078989-BT39 which is a unique

serial number for one copy of the software. Just using this number would be

easily guessed. How do I process the serial number to produce a unique

number?

Any ideas.

dixie